WRT Lithuim Ion, bad advice. Comsumer lithium Ion has average of ~300 cycle, costs more, takes even more complex chargers, limits the devices due to less standardization, etc. Look at my bob and gear pack now, I'd need to carry about 10 different chargers if I switched everything from AA to lithium Ion. CPF loves Lithuim Ion because they tend to use their gear every day, puts run time as the top priority, and had a flashlight centric view of batteries. If you include radios, GPS, etc then lithium ion becomes a poor choice.

Now with NiMH you don't want to treat them like NiCad so don't fully discharge them every use, every 20 is the recommended number now (according to CPF and other sources).

Remember also that even though a charger may be multi channel, smart, etc that it still may not be a good charger. There are various methods used to determine a full charge and better chargers will combine two or more. Also charge within the recommended .5 to 1C, charging too fast generates heat which shortens the life, charging too slow makes the end of charge harder to detect and tends to result in overcharging. So stay away from "fast" or the "slow gentle" chargers.